In this article we tried to collect all possible principles of pump operation. Often, it is quite difficult to understand the wide variety of brands and types of pumps without knowing how a particular unit works. We tried to make this clear, since it is better to see once than to hear a hundred times.
Most descriptions of pump operation on the Internet contain only sections of the flow part (in best case scenario phase operation diagrams). This does not always help to understand exactly how the pump functions. Moreover, not everyone has an engineering education.
We hope that this section of our website will not only help you in making the right choice equipment, but will also broaden your horizons.
Since ancient times, the task of raising and transporting water has been a challenge. The very first devices of this type were water-lifting wheels. It is believed that they were invented by the Egyptians.
The water-lifting machine was a wheel with jugs attached around its circumference. The lower edge of the wheel was lowered into the water. When the wheel rotated around its axis, the jugs scooped up water from the reservoir, and then at the top point of the wheel, the water poured out of the jugs into a special receiving tray. To rotate the device, use the muscular force of a person or animals.
Archimedes (287–212 BC), a great scientist of antiquity, invented a screw water-lifting device, later named after him. This device raised water using a screw rotating inside the pipe, but some water always flowed back, since effective seals were unknown in those days. As a result, a relationship was derived between the tilt of the screw and the feed. When working, you could choose between a larger volume of water being lifted or a higher lifting height. The greater the inclination of the screw, the greater the feed height while reducing productivity.
The first piston pump for extinguishing fires, invented by the ancient Greek mechanic Ctesibius, was described back in the 1st century BC. e. These pumps can rightfully be considered the very first pumps. Until the beginning of the 18th century, pumps of this type were used quite rarely, because... Made of wood, they often broke. These pumps were developed after they began to be made of metal.
With the beginning of the Industrial Revolution and the advent of steam engines, piston pumps began to be used to pump water from mines and mines.
Currently, piston pumps are used in everyday life to lift water from wells and wells, in industry - in dosing pumps and high pressure pumps.
There are also piston pumps, grouped into groups: two-plunger, three-plunger, five-plunger, etc.
They differ fundamentally in the number of pumps and their relative position relative to the drive.
In the picture you can see a triple plunger pump.
Vane pumps are a type of piston pump. Pumps of this type were invented in the mid-19th century.
The pumps are two-way, that is, they supply water without idling.
Mainly used as hand pumps for supplying fuel, oils and water from wells and wells.
Design:
Inside the cast iron body there are the working parts of the pump: an impeller that performs reciprocating movements and two pairs of valves (inlet and outlet). When the impeller moves, the pumped liquid moves from the suction cavity to the discharge cavity. The valve system prevents fluid flow in the opposite direction
Pumps of this type have a bellows (“accordion”) in their design, which is compressed to pump liquid. The design of the pump is very simple and consists of only a few parts.
Typically, such pumps are made of plastic (polyethylene or polypropylene).
The main application is pumping out chemically active liquids from barrels, canisters, bottles, etc.
The low price of the pump allows it to be used as a disposable pump for pumping caustic and hazardous liquids with subsequent disposal of this pump.
Rotary vane (or vane) pumps are self-priming pumps volumetric type. Designed for pumping liquids. having lubricity (oils, diesel fuel, etc.). Pumps can suck in liquid “dry”, i.e. do not require preliminary filling of the housing with working fluid.
Operating principle: The working body of the pump is made in the form of an eccentrically located rotor having longitudinal radial grooves in which flat plates (vanes) slide, pressed against the stator by centrifugal force.
Since the rotor is located eccentrically, when it rotates, the plates, being continuously in contact with the wall of the housing, either enter the rotor or move out of it.
During operation of the pump, a vacuum is formed on the suction side and the pumped mass fills the space between the plates and is then forced into the discharge pipe.
Gear pumps with external gears are designed for pumping viscous liquids with lubricity.
The pumps are self-priming (usually no more than 4-5 meters).
Operating principle:
The drive gear is in constant mesh with the driven gear and causes it to rotate. When the pump gears rotate in opposite directions in the suction cavity, the teeth, leaving mesh, form a vacuum (vacuum). Due to this, liquid enters the suction cavity, which, filling the cavities between the teeth of both gears, moves the teeth along the cylindrical walls in the housing and is transferred from the suction cavity to the discharge cavity, where the teeth of the gears, engaging, push the liquid from the cavities into the discharge pipeline. In this case, tight contact is formed between the teeth, as a result of which the reverse transfer of liquid from the discharge cavity to the suction cavity is impossible.
The pumps are similar in principle to a conventional gear pump, but have more compact dimensions. One of the disadvantages is the difficulty of manufacturing.
Operating principle:
The drive gear is driven by the electric motor shaft. By engaging the pinion gear teeth, the outer gear also rotates.
When rotating, the openings between the teeth are cleared, the volume increases and a vacuum is created at the inlet, ensuring the suction of liquid.
The medium moves in the inter-tooth spaces to the discharge side. The sickle, in this case, serves as a seal between the suction and discharge sections.
When a tooth is inserted into the interdental space, the volume decreases and the medium is forced out to the outlet of the pump.
Lobe (lobe or rotary) pumps are designed for gentle pumping of high products containing particles.
The different shapes of the rotors installed in these pumps allow pumping liquids with large inclusions (for example, chocolate with whole nuts, etc.)
The rotation speed of the rotors usually does not exceed 200...400 revolutions, which allows pumping products without destroying their structure.
Used in the food and chemical industries.
In the picture you can see a rotary pump with three-lobe rotors.
Pumps of this design are used in food production for gentle pumping of cream, sour cream, mayonnaise and similar liquids that can damage their structure when pumped by other types of pumps.
For example, when pumping cream with a centrifugal pump (which has a wheel speed of 2900 rpm), it is whipped into butter.
An impeller pump (vane pump, soft rotor pump) is a type of rotary vane pump.
The working part of the pump is a soft impeller, mounted eccentrically relative to the center of the pump housing. Due to this, when the impeller rotates, the volume between the blades changes and a vacuum is created at the suction.
What happens next can be seen in the picture.
The pumps are self-priming (up to 5 meters).
The advantage is the simplicity of the design.
The name of this pump comes from the shape of the working body - a disk curved in a sinusoid. A distinctive feature of sine pumps is the ability to carefully pump products containing large inclusions without damaging them.
For example, you can easily pump compote from peaches with inclusions of their halves (naturally, the size of the particles pumped without damage depends on the volume of the working chamber. When choosing a pump, you need to pay attention to this).
The size of the pumped particles depends on the volume of the cavity between the disk and the pump body.
The pump has no valves. The design is very simple, which guarantees long and trouble-free operation.
Principle of operation:
On the pump shaft, in the working chamber, there is a disk shaped like a sinusoid. The chamber is divided from above into 2 parts by gates (to the middle of the disk), which can move freely in a plane perpendicular to the disk and seal this part of the chamber, preventing liquid from flowing from the pump inlet to the outlet (see figure).
When the disk rotates, it creates a wave-like movement in the working chamber, due to which the liquid moves from the suction pipe to the discharge pipe. Due to the fact that the chamber is half divided by gates, the liquid is squeezed into the discharge pipe.
The main working part of an eccentric screw pump is a screw (gerotor) pair, which determines both the operating principle and all the basic characteristics of the pump unit. The screw pair consists of a stationary part - the stator, and a moving part - the rotor.
The stator is an internal n+1-lead spiral, usually made of elastomer (rubber), inseparably (or separately) connected to a metal holder (sleeve).
The rotor is an external n-lead spiral, which is usually made of steel with or without subsequent coating.
It is worth pointing out that the most common units at present are those with a 2-start stator and a 1-start rotor; this design is classic for almost all manufacturers of screw equipment.
An important point is that the centers of rotation of the spirals of both the stator and the rotor are shifted by the amount of eccentricity, which makes it possible to create a friction pair in which, when the rotor rotates, closed sealed cavities are created inside the stator along the entire axis of rotation. In this case, the number of such closed cavities per unit length of the screw pair determines the final pressure of the unit, and the volume of each cavity determines its productivity.
Screw pumps are classified as positive displacement pumps. These types of pumps can pump highly viscous liquids, including those containing large amounts of abrasive particles.
Advantages of screw pumps:
- self-priming (up to 7...9 meters),
- gentle pumping of liquid that does not destroy the structure of the product,
- the ability to pump highly viscous liquids, including those containing particles,
- the possibility of manufacturing the pump housing and stator from various materials, which allows you to pump aggressive liquids.
Pumps of this type are widely used in the food and petrochemical industries.
Pumps of this type are designed for pumping viscous products with solid particles. The working body is a hose.
Advantage: simple design, high reliability, self-priming.
Principle of operation:
When the rotor rotates in glycerin, the shoe completely pinches the hose (the working body of the pump), located around the circumference inside the housing, and squeezes the pumped liquid into the main line. Behind the shoe, the hose regains its shape and sucks up the liquid. Abrasive particles pressed into elastic inner layer hose, then are pushed into the stream without damaging the hose.
Vortex pumps are designed for pumping various liquid media. the pumps are self-priming (after filling the pump housing with liquid).
Advantages: simplicity of design, high pressure, small size.
Operating principle:
Working wheel vortex pump It is a flat disk with short radial straight blades located on the periphery of the wheel. The body has an annular cavity. The internal sealing protrusion, tightly adjacent to the outer ends and side surfaces of the blades, separates the suction and pressure pipes connected to the annular cavity.
When the wheel rotates, the liquid is carried away by the blades and at the same time twists under the influence of centrifugal force. Thus, in the annular cavity of a working pump, a kind of paired annular vortex motion is formed, which is why the pump is called a vortex pump. A distinctive feature of a vortex pump is that the same volume of liquid moving along a helical trajectory, in the area from the entrance to the annular cavity to the exit from it, repeatedly enters the inter-blade space of the wheel, where each time it receives an additional increment of energy, and therefore, and pressure.
Gas lift (from gas and English lift - to raise), a device for lifting droplet liquid using the energy contained in the compressed gas mixed with it. Gas lift is used mainly for lifting oil from drilling wells, using gas coming out of oil-bearing formations. There are known lifts in which atmospheric air is used to supply liquid, mainly water. Such lifts are called airlifts or mamut pumps.
In a gas lift, or air lift, compressed gas or air from a compressor is supplied through a pipeline, mixed with liquid, forming a gas-liquid or water-air emulsion, which rises through the pipe. Mixing of gas and liquid occurs at the bottom of the pipe. The action of gas lift is based on balancing a column of gas-liquid emulsion with a column of droplet liquid based on the law of communicating vessels. One of them is a borehole or reservoir, and the other is a pipe containing a gas-liquid mixture.
Diaphragm pumps are classified as positive displacement pumps. There are single and double diaphragm pumps. Double-diaphragm, usually available with a drive from compressed air. Our picture shows just such a pump.
The pumps are simple in design, self-priming (up to 9 meters), and can pump chemically aggressive liquids and liquids with a high content of particles.
Principle of operation:
The two diaphragms, connected by a shaft, are moved back and forth by alternately blowing air into the chambers behind the diaphragms using an automatic air valve.
Suction: The first membrane creates a vacuum as it moves away from the housing wall.
Pressure: The second membrane simultaneously transfers air pressure to the fluid contained in the housing, pushing it towards the outlet. During each cycle, the air pressure is back wall the releasing membrane is equal to the pressure, pressure from the liquid. Therefore, diaphragm pumps can also be operated with the outlet valve closed without compromising the service life of the diaphragm.
Screw pumps are often confused with screw pumps. But it's perfect different pumps, as can be seen in our description. The working body is the auger.
Pumps of this type can pump liquids of medium viscosity (up to 800 cSt), have good suction capacity (up to 9 meters), and can pump liquids with large particles (the size is determined by the pitch of the screw).
They are used for pumping oil sludge, fuel oil, diesel fuel, etc.
Attention! NON-SELF-PRIMING pumps. To operate in suction mode, the pump housing and the entire suction hose must be primed)
Centrifugal pump
Centrifugal pumps are the most common pumps. The name comes from the principle of operation: the pump operates due to centrifugal force.
The pump consists of a casing (snail) and an impeller with radial curved blades located inside. The liquid enters the center of the wheel and, under the influence of centrifugal force, is thrown to its periphery and then discharged through the pressure pipe.
Pumps are used to pump liquid media. There are models for chemically active liquids, sand and sludge. They differ in body materials: used for chemical liquids various brands stainless steels and plastics, for slurries - wear-resistant cast iron or rubber-coated pumps.
The widespread use of centrifugal pumps is due to the simplicity of their design and low manufacturing costs.
Multi-section pump
Multi-section pumps are pumps with several impellers arranged in series. This arrangement is needed when high outlet pressure is required.
The fact is that a conventional centrifugal wheel produces maximum pressure 2-3 atm.
Therefore, to obtain higher pressure values, several centrifugal wheels installed in series are used.
(essentially, these are several centrifugal pumps connected in series).
These types of pumps are used as submersible well pumps and as high-pressure network pumps.
Three Screw Pump
Three-screw pumps are designed for pumping liquids with lubricity, without abrasive mechanical impurities. Product viscosity - up to 1500 cSt. Pump type: positive displacement.
The operating principle of a three-screw pump is clear from the figure.
Pumps of this type are used:
- on ships of the sea and river fleet, in engine rooms,
- in hydraulic systems,
- in technological lines for fuel supply and pumping of petroleum products.
Jet pump
A jet pump is designed to move (pump out) liquids or gases using compressed air (or liquid and steam) supplied through an ejector. The operating principle of the pump is based on Bernoulli's law (the higher the speed of fluid flow in the pipe, the lower the pressure of this fluid). This determines the shape of the pump.
The design of the pump is extremely simple and has no moving parts.
Pumps of this type can be used as vacuum pumps or pumps for pumping liquids (including those containing inclusions).
To operate the pump, a compressed air or steam supply is required.
Jet pumps powered by steam are called steam-jet pumps; those powered by water are called water-jet pumps.
Pumps that suck out a substance and create a vacuum are called ejectors. Pumps pumping a substance under pressure - injectors.
This pump operates without power supply, compressed air, etc. The operation of this type of pump is based on the energy of water flowing by gravity and the hydraulic shock that occurs during sudden braking.
Operating principle of a hydraulic ram pump:
Along the suction inclined pipe, the water accelerates to a certain speed, at which the spring-loaded baffle valve (on the right) overcomes the force of the spring and closes, blocking the flow of water. The inertia of abruptly stopped water in the suction pipe creates a water hammer (i.e., the water pressure in the supply pipe increases sharply for a short time). The magnitude of this pressure depends on the length of the supply pipe and the speed of water flow.
The increased water pressure opens the top valve of the pump and part of the water from the pipe passes into the air cap (rectangle on top) and the outlet pipe (to the left of the cap). The air in the bell is compressed, accumulating energy.
Because The water in the supply pipe is stopped, the pressure in it drops, which leads to the opening of the baffle valve and the closing of the top valve. After this, the water from the air cap is pushed out by the pressure of compressed air into the outlet pipe. Since the rebound valve has opened, the water accelerates again and the pump cycle repeats.
Scroll Vacuum Pump
The scroll vacuum pump is a positive displacement pump that compresses and moves gas internally.
Each pump consists of two high-precision Archimedes spirals (crescent-shaped cavities) located at an offset of 180° relative to each other. One spiral is stationary, and the other is rotated by a motor.
The moving spiral performs orbital rotation, which leads to a consistent reduction in gas cavities, compressing and moving gas along a chain from the periphery to the center.
Spiral vacuum pumps belong to the category of “dry” foreline pumps, which do not use vacuum oils to seal mating parts (no friction - no oil needed).
One of the areas of application for this type of pump is particle accelerators and synchrotrons, which in itself already speaks about the quality of the vacuum created.
Laminar (disc) pump
A laminar (disc) pump is a type of centrifugal pump, but can perform the work not only of centrifugal pumps, but also of progressive cavity pumps, vane and gear pumps, i.e. pump viscous liquids.
The impeller of a laminar pump consists of two or more parallel disks. The greater the distance between the discs, the more viscous the liquid the pump can pump. Theory of the physics of the process: under laminar flow conditions, layers of liquid move at different speeds through a pipe: the layer closest to the stationary pipe (the so-called boundary layer) flows more slowly than the deeper (close to the center of the pipe) layers of the flowing medium.
Similarly, when fluid enters a disc pump, a boundary layer forms on the rotating surfaces of the parallel impeller disks. As the disks rotate, energy is transferred to successive layers of molecules in the fluid between the disks, creating velocity and pressure gradients across the width of the orifice. This combination of boundary layer and viscous drag results in a pumping torque that "pulls" the product through the pump in a smooth, almost pulsating flow.
*Information taken from open sources.
EVN5 submersible screw electric pump units of all standard sizes are manufactured according to the same design diagram with two working bodies connected in parallel, which provides:
- - doubling the feed with the same transverse dimensions;
- - the working bodies (screw pairs) are hydraulically mutually balanced, which eliminates the transfer of significant axial forces to the pump support bearings and the electric motor heel.
The EVN5 submersible screw electric pump unit (Figure 5) consists of the following elements: starting claw clutch centrifugal action, a base with a drive shaft, strainers installed at the pump inlet, working elements with right and left cages and screws, two eccentric swivel couplings, a safety valve and a slurry pipe.
When the unit is operating, the torque from the electric motor is transmitted to the working screws through the hydraulic protection protector shaft, the starting clutch and the eccentric couplings of the pump. According to the principle of operation, pumps are classified as positive displacement, and according to the method of transferring energy to liquid, they are classified as rotary. The main working bodies are single-thrust helical rotors with a right and left spiral direction and two rubber-metal cages, the internal cavity of which is a two-threaded screw surface with a pitch 2 times greater than the pitch of the screw, made of oil-gasoline-resistant rubber or other elastomer.
The operating principle of the pump is that a series of closed cavities are formed between the screw and the holder along the entire length, which, when the screw rotates, are filled with the pumped liquid, moving from the pump intake to its discharge. The screws rotate around their axis and in a circle with a radius equal to the eccentricity.
The liquid enters simultaneously into the left and right parts of the pump through receiving mesh filters. In the chamber between the screws, the flows are connected, and following further along the annular channel between the pump body and the upper casing, the liquid enters the pressure line through the safety valve.
Reservoir fluid is pumped practically without pulsation, without creating a stable emulsion of oil and water. The pump flow is equal to the sum of the flows of the working pairs, and the pump pressure is equal to the pressure of each working pair.
All main components and parts of diaphragm pumps are unified and are used, with some exceptions, in all pumping units.
Screw pumps of the EVN5 type have a number of specific parts: a starting cam clutch, eccentric swivel couplings, a safety valve, a slurry pipe, a strainer.
Starting jaw clutch centrifugal type connects the protector and pump shafts and, using retractable cams, ensures that the pump starts when the maximum torque is moving on the engine shaft, corresponding to a rotation speed of 800-1200 rpm.
This is due to the fact that the screw pump has a large static inertia and, in order to start it (overcome frictional forces), an increased starting torque is required. In addition, the starting clutch does not allow the pump shaft to rotate in the opposite direction.
During reverse rotation due to the bevel on the cams, the clutch does not engage, and the cams slip and thereby protect the pump from turning loose threaded connections. The coupling also protects the pump from emergency operation, because When one of the working parts fails, the last one is switched off. Inside the pump base there is a shaft with bearings and support feet made of siliconized graphite.
There is no oil seal at the base, and the rubbing surfaces are lubricated with formation fluid. The drive shaft is fitted with protective bushings made of stainless steel, which rotate in bronze bushings. The fixed end heels rest on rubber pads to uniformly transfer forces to the entire surface of the heel.
The eccentric clutch allows for complex planetary rotation in the cages. Due to this, the liquid is pushed along the axis of the screw and creates required pressure to lift liquid to the surface.
At the top of the pump there is a spool safety valve, which consists of a housing, spool, piston, shock absorber and housing parts. The valve performs the following functions:
- - passes liquid into the tubing string when lowering the pumping unit into the well;
- - ensures drainage of liquid from the tubing string when lifting the unit from the well;
- - prevents the drainage of liquid from the pipe string through the working parts of the pump when the pump is stopped (all liquid is drained through the valve into the annulus);
- - protects the pump from dry friction and high pressure in the pressure line;
- - ensures the bypass of liquid from the pressure line back into the well either when there is insufficient flow of liquid from the formation, or when the liquid contains a large amount of gas.
The slurry pipe protects the pump from mechanical impurities and scale that fall out of the tubing string when the pump is stopped, installed, and acts as a sump.
Purpose and scope of pumps
Submersible screw pump units with a surface drive are often called UShVN (rod screw pump units) and are designed for pumping high-viscosity formation fluid from oil producing wells.
The installation is a submersible rod pump (SRP), the stator of which is fixedly attached to the tubing string, and the screw to the rod string. A valve assembly is attached to the bottom of the stator. Surface equipment includes a column head, a preventer-tee, a gearbox, a modular insert, and an electric motor.
The rotation of the screw is carried out by a string of rods located inside the tubing string, from a ground drive consisting of a rotator (gearbox) and an electric motor.
The screw pump provides high performance when pumping high-viscosity liquid with a high gas factor and a significant content of mechanical impurities.
In directional wells, to reduce friction forces and wear of tubing pipes, centralizing couplings are installed, which act as intermediate radial supports and can be presented in two designs:
- - non-separable, placed directly on a full-size or shortened rod along special technology in factory conditions;
- - dismountable, installed between the couplings of standard rods.
It is most rational to use rod centralizers, ensuring their immobility relative to the tubing string, which leads to a reduction in energy consumption and pipe wear. Several lower rods located directly close to the eccentrically rotating rotor are not equipped with centralizers.
A rational area of application for water pressure pumps is vertical wells or wells with low rates of curvature development with high-viscosity formation fluids with a high content of gas and mechanical impurities. Most often, pump pumps are used for flow rates from 3 to 50-100 m3/day with a head of up to 1000-1500 m, however, some standard sizes of pump pumps can have much greater production capabilities.
Screw pumps for wells are a type of device where water is displaced by one or a pair of rotors that achieve the required pressure. The rotor produces revolutions in a suitable type of stator. Screw pumps are positive displacement pumps. Screw devices are called rotary-geared. They are most often produced using gear pumps by reducing the number and increasing the angle of gears.
The screw pump is positive displacement
The main purpose of the described devices is pumping petroleum products. Pumping screw designs are engaged in pumping fuel oil, oil, oil, diesel fuel, paraffin. Pumping screw devices are used in various fields. They process slag, help produce tobacco products, textile and paper products, food and chemical items, and process iron products.
Screw pumping devices for wells have not gained much popularity as the main hydraulic pumps in machines.
Device typology
Screw borehole pumps are divided into several types.
- Single screw pumps – horizontal pumps; type – volumetric. Such devices are made from a rubber “hoop” and a single-thread metal screw, which rotates in a cage. When rotation occurs, spaces appear between the parts where water enters and is pumped. After getting there, the water moves into the injection cavity.
- Pumps made of two screws are designs that are used most often for marine, fresh, and mineral pumping of liquids.
- Fuel oil models with two screws are devices used primarily for pumping fuel oil and other viscous liquids. It features a single mechanical seal, a heating jacket, and a durable steel part.
- Pumps made of three screws - designs work with non-aggressive liquids with lubricity and abrasive mechanical impurities in the composition. Works in horizontal and vertical positions.
It is not uncommon for screw devices to be called screw devices, combining them into one unit, this should not be done, because the devices are different in type of operation. A screw pump is also characterized by a displacement action, but it is dynamic, unlike a screw device.
Screw pumps are distinguished by a gerotor screw pair. It deals with determining the properties of the device and determining the mechanism of operation of the pump. The screw pair includes a static element, the stator, and a moving part, the rotor.
The most popular are devices with a double-start stator and a single-start rotor.
Screw screw pump pumps heterogeneous substances
Screw screw pump is indispensable for working with a variety of substances of dissimilar nature, and has a sufficient number of advantages. In some areas it is sometimes impossible to use any other pumping units, except for the screw one.
The advantages of a screw screw pump are:
- the described pumping devices are self-priming, they do not require “priming”;
- pumping systems are engaged in pumping heterogeneous substances with mixtures of various substances.
Operation of screw pumps
Screw submersible pumps have a special design. They consist of the following components:
- drive type gear motor;
- transition stand;
- stator-rator pair;
- pressure pipe;
- camera;
- hinge;
- sealing type gross component.
The main working part of the structure is considered screw pair. The elastomeric stator is connected to a metal rotor inside. Due to rotational movements, changes occur in the volume of the cavity in the steam; water moves along the axis of the pumping device. Liquids are displaced and absorption occurs.
To improve the quality of sealing of the pumping device and reduce the level of leaks, the design is equipped with a flexible conical or cylindrical body. It is worth noting that the elastic design of the pump copes with much less pressure compared to a metal structure. Among other things, the structure includes secondary elements, seals, bearings and nuts.
Screw pumps operate according to clearly described principles and under specific conditions. The main characteristics include:
- Temperature characteristics. The stator of the pumping device is responsible for determining the highest level of water temperature. Note that the temperature can be determined by the nature of the liquids and the operating conditions of the pumping device.
- A screw installation is considered a self-priming device.
- Feed characteristics. Such devices are distinguished by their volumetric operating principle. Thanks to this, the supply of substances occurs regularly, smoothly and without sudden fluctuations.
In order for the pumps to operate smoothly, it is worth talking about the possible volumes of liquids for operation. Screw designs are different increased level stability due to a high-quality stator. These pumps can be used when pumping any viscous liquid, as well as when pumping water with solid particles. Such complications will not result in cessation of work or loss of performance.
To protect the stator, you need to fill the pump with a special pumping liquid. Having done this, check the condition of the valves. They must be open. Regarding a pump with a regularly operating motor, in order to regulate the movement of material flows, you need to set a certain flow rate or install a control valve.
The operation of the screw pump must be as safe as possible
It is very important to ensure safe work with pumping devices. Follow simple precautions, including the pump, to ensure your equipment lasts a long time.
- It is strictly forbidden to turn on the system without liquids in it. Subsequently, deformation of the stator may occur.
- Do not adjust the flow rate of the device by closing the valve. This action has side properties in the absence of protection - deformation of drive mechanisms and engines.
Positive aspects of screw pumps
It is worth noting that screw installations have a number of positive characteristics and reviews. Many users note the effectiveness of such devices. We'll talk about the advantages and disadvantages further.
Positive aspects and features of the design:
- They are durable. Due to the fact that the electric motor is engaged in the movement of the screw, and it does not have to have contact with the “insides” of the device, friction is reduced to a minimum. This contributes to the longevity of the work.
- Axial flow of medium movement in the device. This ensures that the emerging “product” can move smoothly and there is no pulsation.
- The devices have low noise pollution characteristics. Due to the low inertia of the moving parts of the device, the starting torque will also have low values.
- The units have good suction characteristics.
- The design of powerful devices is equipped with safety valves. They are needed for the safe operation of pumps and the entire structure as a whole. Valves are needed for those options if pressure is exceeded.
- The liquid is supplied evenly, which makes screw pumps better than piston and plunger pumps.
- Screw pumps are characterized by their simplicity of design, ease of use and maintenance.
- Screw structures are capable of sucking liquid from ten meters deep.
- Screw installations are characterized by a high-quality mechanism.
- The pumps are easy to operate.
Minor cons
Among several disadvantages, the following are noted:
- when working with screw pumps, it is impossible to adjust the working volume;
- difficulties are observed when working with other species;
- screw models have worse overall dimensions and weight;
- have a high price.
What should you think about first when choosing a pump design?
How well the pump works for you depends on the following important factors:
- on the type of installation of the structure and its characteristics of use;
- on the flow rate of the pumped liquid;
- from the pressure indicator;
- depends on what substance will be pumped: we are talking about density, composition, temperature and viscosity.
Choose equipment wisely, and it will definitely serve you for a long time and with high quality, because a lot really depends on what criteria you use when choosing.
The screw pump (CP), a liquid transfer device, was developed in the early 1920s for pumping viscous liquids and solutions. From the very beginning, screw pumps have been widely used in a wide variety of conditions and used in various industries (chemical, food, metalworking, paper, textile, tobacco, waste processing and oil).
Since the first serious attempts to use progressive cavity pumps for artificial lift in the early 1980s, they have been gradually introduced into the oil industry.
By 2003, PCPs were operating in a wide variety of conditions and completions in more than 40,000 wells worldwide, from Alaska to South America, from light oil and coalbed methane production in Russia's Nizhnevartovsk and Novokuznetsk to Australia, from remote mineral springs in mountains of Japan to onshore and offshore wells in Africa and Indonesia. Below are standard options and conditions for using screw pumps:
Heavy oil
Density in API degrees Absolute viscosity 500 - 50000 cP
Sand content up to 50%, reduced to 3-5% with stable flow rate
Medium density oil
Density in degrees according to API 18 - 30
Absolute viscosity CO2 and H2S limits
Light oil
API gravity >30
Limitation of aromatic hydrocarbons content
Temperature restrictions
Water
Coalbed methane (CBM) dehydration
Natural gas dehydration
Water wells
- Heating of residential premises
- Industrial sources of mineral waters
Water injection - flooding
Progressive cavity pump systems have a range of distinctive features, which may make them preferable for mechanized mining compared to other available technical means. Here are the most significant of these features:
- The efficiency of screw pump systems is 50 - 70%
- Low capital and energy costs
- Possibility of pumping liquids from high level viscosity, high content of solid particles and free gas
- Low internal shear rate gradients limiting fluid emulsification
- No valves or reciprocating parts prevent clogging, gas locking or component wear
- Easy installation and operation, minimal maintenance required
- Small dimensions and low noise level of the drive unit at the wellhead.
Screw pump systems have a number of certain restrictions on the conditions of use. Chief among these limitations are capacity, liquid lift height, and compatibility of rubber parts with the fluids being pumped. Below is a short list of the restrictive application conditions and operational problems associated with the use of HV systems.
- Capacity: 1-800 m3/day (5000 barrels/day)
- Liquid lift height: 3000 m (9800 ft)
- Temperature: 150°C (300°F)
- There is a tendency for irreparable damage to elastomeric parts to occur when the pump is operated without liquid, even for a very short time.
- Exposure to certain liquids causes swelling and deterioration of the elastomeric material
The use of improved equipment and materials allows us to significantly expand the range of application of screw pumps of new models. In many cases, VN is not only the only possible option mechanized operation, but can also become very effective from an economic point of view with optimal configuration and proper operation.
Basic principles of operation of a screw pump
The screw pump is a positive displacement pump consisting of two components - a rotor and a stator (Fig. 1). The rotor has the shape of an outer spiral with the number of starts "n" and is usually made of high-strength steel (Fig. 2). The rotor is the only moving part of the pump. The stator is an internal spiral with the number of entries “n+1” (Fig. 3) and consists of a steel casing-pipe with an elastomer element permanently connected to the walls of the pipe. The rotor has one less turn than the stator.
When they are assembled together, a group of biconvex cavities, spiraling around the outside of the rotor, extends along the helical line of the pump (Fig. 4). Each cavity is hermetically separated from adjacent cavities using sealing lines. Sealing lines are formed along the contact line between the rotor and stator (shown in red) and are important point For efficient work pump Rice. 4 shows two separate cavities at one stator pitch at 180° to each other in a pump with a single-throw rotor.
Operating principle of a screw pump
As the rotor rotates, the cavities constantly open and close and move from intake to pump delivery. The cavity area between the rotor and stator remains constant at any cross section along the entire length of the pump, which ensures non-pulsating flow. The cavity volume is defined as the injection area (area cross section cavity) multiplied by the stator pitch. The rotor centerline is offset from the stator axis by a constant amount called "eccentricity". For a pump with single-pass geometry, the eccentricity is equal to the difference between the major and minor rotor diameters divided by two. The cavity area of a pump with single-pass geometry is equal to the small diameter of the rotor multiplied by 4 and multiplied by the eccentricity. The cavity volume is determined as a function of the cavity area multiplied by the stator pitch.
Cavity area = d x 4e
Cavity volume = d x 4e x stator pitch
Pressure characteristics and change in pump flow when pressure changes
Nominal level differential pressure screw pump is the sum of the rated pressure levels of each individual stage. Although a somewhat arbitrary definition, a step is usually referred to as the length of one stator pitch. Typically the pressure rating for an individual stage is in the range of 66-100 psi. Combination a) maximum level pressure that can be created in one cavity and b) the number of cavities in the pump determines its maximum pressure. The pressure that can be generated in each cavity is a function of the rotor and stator compression fit, the physical characteristics of the elastomeric element, the stator pitch length, and the properties of the fluid being pumped. For a screw pump, other things being equal, more high pressure for each stage usually means lower stator life.
Most commonly used measurement method performance characteristics pump is the calculation of the volumetric efficiency of the pump, defined as the difference between the initial pump flow at zero head and the flow at rated head divided by the initial flow at zero head. The difference in flow levels at zero and rated heads is defined as “the change in pump flow with a change in pressure.” Pump flow variation with pressure changes occurs when high-pressure fluid breaks the compression fit between adjacent cavities and breaks between the rotor/stator seal line. This results in an overall reduction in the pump's flow rate, which is constant for a given value of differential pressure.
Screw pump
Internal organization three screw pump
Screw or screw pump- a pump in which the pressure of the injected liquid is created by displacing the liquid by one or more screw metal rotors rotating inside a stator of the appropriate shape.
Screw pumps are a type of rotary gear pump and are easily obtained from gear pumps by reducing the number of gear teeth and increasing the angle of inclination of the teeth.
Design of screws in a twin-screw pump. The liquid moves along the axis of the pump
Principle of operation
Pumping of liquid occurs due to its movement along the axis of the screw in the chamber formed by the screw grooves and the surface of the housing. The screws, by inserting their helical projections into the grooves of the adjacent screw, create a closed space, preventing the fluid from moving backwards.
Application area
Designed for pumping liquids of varying degrees of viscosity, gas or steam, including their mixtures.
These pumps can operate at pressures up to 30 MPa.
First introduced into practice in 1936, screw pumps have a simple design and can operate in the presence of mechanical impurities and with viscous fluids, which is necessary when solving various practical problems. Big number Screw pump units (CPU) are used to remove water from wells that produce methane from coal seams, primarily due to their ability to pump liquids with mechanical impurities. However, screw pumps are also suitable for other gas wells, as well as for water and oil production.
Design features
To improve the quality of seals and reduce leakage, a cylindrical or conical elastic body is sometimes used. In the latter case, the conical screw is pressed by a spring, and sometimes also by the pressure of the pumped liquid. However, pumps with an elastic casing can withstand lower pressures than pumps with a metal casing. In pumps with conical screws, a rigid casing can be used.
The most common are three-screw pumps.
Advantages
- uniform supply of liquid, unlike piston and plunger pumps;
- the ability to pump mixtures of liquid and solid phases without damaging solid inclusions in the liquid;
- like other positive displacement pumps, screw pumps have the ability to self-prime liquid;
- the ability to obtain high outlet pressure without many injection cascades;
- good balance of the mechanism and, as a result, low noise level during operation.
Flaws
- complexity and high cost of pump manufacturing;
- unregulated working volume;
- just like other types of volumetric pumps, screw pumps cannot be run idle without pumped liquid, since in this case the coefficient of friction of the pump parts increases and the cooling conditions worsen; As a result, the pump may overheat and fail.
Literature
1.Skhirtladze A.G., Ivanov V.I., Kareev V.N. Hydraulic and pneumatic systems. - 2nd edition, supplemented. M.: IC MSTU "Stankin", "Janus-K", 2003 - 544 p.
2.Lee James, Nickens Henry, Wells Michael. Operation of flooded gas wells. Technological solutions for removing fluid from wells / Translation from English. - M.: Premium Engineering LLC, 2008. - 384 p., ill. (Industrial Engineering).
see also
- PCM Progressive Progressive Pumps
Notes
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See what a "screw pump" is in other dictionaries:
A rotary pump with working bodies in the form of one driving and usually two driven screws in mesh. When the screws rotate, the liquid cut off in the cavities of the screw thread moves along the screws and is pushed into the pressure pipe... Big Encyclopedic Dictionary
screw pump- Rotary rotation pump with movement of the liquid medium along the axis of rotation of the working bodies. [GOST 17398 72] Inadmissible, not recommended worm pump Topics pump EN screw pump DE Schraubenspindelpumpe FR Pompe a vis ... Technical Translator's Guide
A rotary pump with working bodies in the form of one driving and usually two driven screws in mesh. When the screws rotate, the liquid cut off in the cavities of the screw thread moves along the screws and is pushed into the pressure pipe... encyclopedic Dictionary
screw pump- sraigtinis siurblys statusas T sritis automatika atitikmenys: engl. screw pump vok. Schraubenpumpe, f rus. screw pump, m pranc. pompe hélice, f … Automatikos terminų žodynas
screw pump- sraigtinis siurblys statusas T sritis Energetika apibrėžtis Rotacinis siurblys, turintis sukamojo judesio darbinius elementus. Sraigtinio siurblio korpuse yra vienas varantysis ir dar vienas, du arba keturi varomieji sraigtai. Didinant slėgį,… … Aiškinamasis šiluminės ir branduolinės technikos terminų žodynas
Rotary pump with rotating movement of working parts (screws). In the building of V. n. there is one driving and one, two or four driven (sealing) screws. The gap between the screw threads and the housing is small. Screw engagement line within one step... ... Big Encyclopedic Polytechnic Dictionary
A hydraulic machine, the working part of which is a screw: used to supply fluid, including those with high viscosity. V. n. is a type of rotary pump, also called worm pump. In the building of V. n. available... ... Great Soviet Encyclopedia
Pump, screw- Screw pump NDP. Worm pump Rotary rotational pump with movement of the liquid medium along the axis of rotation of the working bodies See all terms GOST 17398 72. PUMPS. TERMS AND DEFINITIONS
